Hi Carol and Resa,
I'm sorry that you're having problems with the site. We don't know of any particular issues right now, but we're looking into it. Is it just the Game Lab (Unit 3 levels) that you are having problems with, or are there other parts of the site as well?
Please also feel free to report problems like this as "bugs" using the "Report a Bug" feature. We have extra resources for the website and on our help system right now to deal with any problems that might arise, and we're eager to make sure everyone has a good experience on the site. If that's not the case for you, then we'd like to fix it.